The Frenchman has been out with a knee injury since November, with his last appearance coming in the 3-1 win over Manchester United.
He returned to light training recently as he stepped up his recovery and Pep Guardiola has confirmed he will travel with the squad to Burton and could play some part against the League One side.
However, Vincent Kompany remains sidelined with a muscle problem and is unavailable for selection.
"[Mendy is] in the squad for tomorrow,” Guardiola said. “He will travel with us. Maybe on the bench.
"I would say with the results we have done last two years, we have not missed him too much but I would say we have missed him a lot.
"My feeling is he can give something extra. Hopefully, in the last part of the season and in the future we can use him.
"He pushes from the outside on the left, he is unstoppable. Especially in the last third, he is so clever. He is clever when he does those kind of actions.
"In two seasons he played few and when we talk, practice he is not there. We will need some time to adjust his quality for what we need.
“Kompany is not okay. A little injury - he is not fit.
“He is coming back but i don’t know when.”
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Guardiola insists he will play a strong side at the Pirelli Stadium.
City established a 9-0 lead in the first leg a fortnight ago, leading to suggestions Guardiola would field a team made up largely of academy stars on Wednesday.
But the boss has rejected the idea and says there will be plenty of senior players involved, including Phil Foden and Kevin De Bruyne.
"The guys who have a lot of games in their legs and are going to rest," he said. "Players who need to play, who haven't played lately, who are coming back from injury long-term are going to play.
"We are going to play Phil. Going to play a few [academy players], two or three. A few on the bench.
He [De Bruyne] is going to play.
"Some players need rhythm and will play, the first team."